Installing x-pack on offline machines does not work on logstash

when i try to install x-pack-5.0.2 on logstash 5.0.2 the manager tries to go to

[root@node logstash]# ./bin/logstash-plugin install file:///tmp/
Validating file:///tmp/
Unable to download data from - SocketError: initialize: name or service not known (
ERROR: Installation aborted, verification failed for file:///tmp/

can you confirm what version of Logstash and x-pack you have? Do you mean x-pack 5.0.2 or 5.2.0?

it's 5.0.2
[root@node logstash]# rpm -qa|grep logstash

Logstash x-pack was introduced in 5.2.0, so it will not work when installing on LS 5.0.2.

Please upgrade to Logstash 5.2.0 if you want to install the x-pack.

I just found that out on a node with Internet Access. So i upgraded the whole Stack and it worked.